Code division multiple access (CDMA) techniques transmit multiple information signals on the same channel (carrier frequency), and differentiate each user sub-channel by encoding it with a unique spreading code. CDMA techniques have been employed in many digital wireless communication systems to permit a large number of system users to communicate with one another. CDMA systems treat each user as a separate signal, while treating other users as either interference or noise. As the number of interfering users increases, the corresponding interferences add to cause degradation of performance, such as an increasing bit error rate (BET) or frame error rate.
Multi-carrier CDMA systems are employed for interference avoidance rather than interference averaging. Interference avoidance is more plausible when interfering terminals are likely to get close to each other frequently; a situation which arises in a highly dynamic network such as a cellular network with mobile base stations. In fact, the case of mobile base stations is typical for battlefield networks where a number of Radio Access Points (RAPs) serve as the base station and are deployed in the field to act as switching/routing nodes for traffic generated by mobile terminals in the vicinity of such RAPs. In a commercial setting, it has been proposed to deploy RAPs on trucks or public transportation vehicles, such as buses and the like.
While conventional channel allocation techniques are satisfactory for fixed or stationary base stations, the mobility of the base stations themselves degrades the performance of such conventional channel allocation techniques in the mobile environment of the present invention. Thus, a need exists for a distributed dynamic channel allocation algorithm for multi-carrier CDMA cellular systems having mobile base stations.